Physical Chemistry

Singlet and Triplet Exciton Dynamics of Violanthrone

Abstract

The exciton dynamics of violanthrone-79 are investigated in solution and in the solid
state. In solution, the photo-prepared singlet is found to exhibit a strong ground-state bleach
and stimulated emission feature, but when sensitized in its triplet state, exhibits only a narrow
and weak ground-state bleach. As supported by density functional theory calculations,
this is explained by the triplet state having absorptions in the same region, with a similar
oscillator strength, as the ground state molecule. In solid films, the excited singlet is
found to survive only 100 ps, giving way to a long-lived transient absorption spectrum with
characteristics reminiscent of the triplet in solution. This is interpreted in terms of singlet
fission in the solid film.

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submitted manuscript

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